The Space Shuttle Enterprise, taking a quick trip through New York last month as it prepares for retirement at the Intrepid Sea, Air and Space Museum in New York

NASA is reviewing bids for at least two design
contracts, valued at $300 million to $500 million apiece.

The taxi service will be composed of recycled space shuttle parts along with a new NASA prototype spaceship.

The contracts for NASA's so-called Commercial Crew program, is scheduled to be awarded this summer.

ATK, which built the space shuttle booster rockets, teamed with Astrium, a company that is one of the manufacturers of Europe's Ariane 5 rockets, to bid for NASA space taxi development funds last year but was not selected.

Rominger
said Liberty could be ready to fly crew to the station in 2015 for less
than what Russia charges for rides in its Soyuz capsules.

Rominger said: 'As a taxpayer, I want to get the best value out of what I've invested
into our government. For example, Ares 1 (rocket program) was canceled,
so to now pick up where the government left off is a very smart thing to
do. It brings us the best value as a nation.'

The International Space Station (front) says goodbye to the Endeavour as it heads back to Earth

Taxi driver: This is the pilot's seat of the recently-retired Endeavour, as NASA looks around for a new company to get a lift from

The Liberty rocket's first stage would be an extended space shuttle booster rocket, a design originally developed under NASA's now-canceled Ares 1 rocket program.

Liberty's second-stage engine would be provided by Astrium. The newly announced capsule, also named Liberty, is a composite spaceship developed by NASA as a potential alternative to the Orion deep-space capsule.

Liberty would fly from one of the space shuttle launch pads at the Kennedy Space Center in Florida. Depending on funding, test flights could begin in 2014.

Rominger said the capsules, which would parachute to a water landing, are designed to fly up to 10 times.

In addition to carrying seven astronauts, the rocket and capsule could carry cargo to and from the space station, as well as be used for satellite launches and other missions.

Rominger declined to say how much ATK and its partners have spent developing the Liberty system so far.